Drop sway_output.surface_needs_frame

wlr_output_schedule_frame now sets output->needs_frame [1], so this
isn't needed anymore.

[1]: https://github.com/swaywm/wlroots/pull/2053

include/sway/output.h

@@ -57,7 +57,6 @@ struct sway_output {
 	uint32_t refresh_nsec;
 	int max_render_time; // In milliseconds
 	struct wl_event_source *repaint_timer;
-	bool surface_needs_frame;
 };
 
 struct sway_output *output_create(struct wlr_output *wlr_output);

sway/desktop/output.c

@@ -515,9 +515,6 @@ static int output_repaint_timer_handler(void *data) {
 
 	output->wlr_output->frame_pending = false;
 
-	bool surface_needs_frame = output->surface_needs_frame;
-	output->surface_needs_frame = false;
-
 	struct sway_workspace *workspace = output->current.active_workspace;
 	if (workspace == NULL) {
 		return 0;
@@ -562,10 +559,6 @@ static int output_repaint_timer_handler(void *data) {
 		output_render(output, &now, &damage);
 	} else {
 		wlr_output_rollback(output->wlr_output);
-
-		if (surface_needs_frame) {
-			wlr_output_schedule_frame(output->wlr_output);
-		}
 	}
 
 	pixman_region32_fini(&damage);
@@ -682,7 +675,6 @@ static void damage_surface_iterator(struct sway_output *output, struct sway_view
 	}
 
 	if (!wl_list_empty(&surface->current.frame_callback_list)) {
-		output->surface_needs_frame = true;
 		wlr_output_schedule_frame(output->wlr_output);
 	}
 }